1. Technical Field
The present invention relates to a nut runner having, on its tip end, a socket holder for retaining a socket.
2. Description of the Related Art
A nut runner has, on its tip end, a socket holder for retaining a socket. The socket holder retains a socket having dimensions which are different depending on the dimensions of a nut, bolt, or screw to be fastened or loosened. The socket retained by the socket holder fastens or loosens, for example, a nut.
There is a clearance between the socket and the socket holder of the nut runner, which typically causes a backlash, when the nut runner rotates, because the socket is relatively long. Japanese Unexamined Utility Model Publication (U. M. Kokai) No. 6-36728 discloses that a bearing provided on the inner surface of a socket holder prevents a backlash.
However, in U. M. Kokai No. 6-36728, a clearance still remains between a socket and a socket holder. This may cause the socket to incline, due to its weight, with respect to the center axis of a nut runner when the nut runner is used horizontally. Thus, the axis of the nut runner tends to deviate greatly, and positioning of the socket is difficult.
In view of these problems, it is an object of the present invention to provide a nut runner in which a core runout is prevented and a socket can be easily positioned even when the nut runner is used horizontally.